1. Field of the Invention
This invention relates to radar and more particularly to a radar that provides a beam which scans a spatial region and provides little spurious radiation.
2. Description of the Prior Art
In a military operation on land, it is usually desirable to have a radar that is mobile, light, small and thereby suitable for deployment near a battlefield. Moreover, spurious radiation from the antenna of the radar is preferably minimized to prevent destruction of the radar by radiation seeking missiles and to prevent interference caused by jammers. Spurious radiation is represented by side lobes in a radiation pattern of an antenna.
As known to those skilled in the art, much of the weight and bulk of the radar is in the antenna. A fixedly mounted antenna, such as a phased array antenna, usually includes a large number of components, thereby causing the phased array antenna to be heavy and bulky. Because of its weight and bulk, the phased array antenna is not suitable for deployment near the battlefield. An offset fed paraboloid reflector antenna has been considered for use with the radar because the paraboloid reflector antenna does not have the heavy weight and bulk of alternative types of antennas.
The paraboloid reflector antenna has been used on satellites. Typically, the paraboloid reflector antenna includes a plurality of radiators that are disposed near the focal point of the paraboloid reflector. The disposition of the radiators is selected to cause the propagation of a beam of electromagnetic energy to a known portion of the earth in response to excitation being applied to the radiators. Usually, the paraboloid reflector antenna is not symmetric with respect to the axis of the antenna, thereby preventing an occlusion of the beam by the radiators.